Usually, a PM BLDC motor includes a stator and a rotor rotatable with respect to the stator. The rotor has at least one permanent magnet installed thereon. The stator comprises a stator core and windings wound on the stator core. The windings generate a magnetic field which coacts with the permanent magnets to drive the rotor to rotate relative to the stator. The rotor may be a so called surface mounted permanent magnet rotor in which the magnet(s) are mounted on the surface of the rotor core or a so called interior permanent magnet (IPM) rotor, in which the magnets are located in holes formed in the rotor core.